Some of conventional electric vacuum cleaners, especially upright (or vertical type) vacuum cleaners are equipped with a dust collecting case, detachably installed in a suction passage, for accumulating dust in a cylindrical filter fitted in the dust collecting case. The accumulated dust is removed by opening a lid of the dust collection unit. Such dust collection unit is economical as compared with a disposable paper bag in that the unit can be used semipermanently.
An example of this type of vacuum cleaners is disclosed in Japanese Patent Application Early Publication 2000-342492 (A47L 9/10).
In this cleaner, the lid of a dust collecting case is configured to be opened by the weight of the dust itself accumulated in the dust collecting case when a clamp hook locking the lid is unlocked.
This type of dust collection unit is provided with a packing for sealing the periphery of the lid to prevent leakage of dust. In order to enhance the sealing, the sealing pressure of the packing must be raised. However, if the sealing pressure is raised, movement of the lid will become heavy. Furthermore, as the amount of dust accumulated in the dust collecting case increases, the dust will be compacted on the inner wall of the dust collecting case, thereby failing to weigh on the lid. For these reasons, the lid will not always open by itself if the lid is unlocked by releasing the clamp hook, and, in that event, it must be forcibly opened by hand. This work is tedious and unsanitary.